Aging does not Affect Radial Viscoelastic Behavior of the Left Ventricle.

Objectives: This study investigates the effect of aging on the radial viscoelastic behavior of the left ventricle (LV) based on a previously validated model that uses myocardial tissue phase mapping (TPM) of cine phase-contrast MRI. Methods: Previous studies suggest that aging remarkably influences regional myocardial motion, mostly myocardial velocities in both radial and long-axis directions. However, the effect of aging on cardiac viscoelasticity, which exhibits time-dependent strain, has not been elucidated yet. In this study, myocardial velocity and displacement mapping of the LV was performed using TPM in 39 healthy subjects divided into three age groups. The viscoelasticity parameters were obtained for each segment of the LV and compared among the studied groups. Results: The analyses showed that myocardial elasticity ranged from approximately 20 to –20 dyne/cm 2 during a cardiac cycle, and the myocardial viscousdamping component ranged from –1 to 1 dyne × s/cm 2 . Overall, no statistically significant difference was observed in the viscoelasticity components among the subjects in the different age groups (p > 0.05). Conclusion: Myocardial viscoelastic behavior of the LV in radial direction was found to be considerably similar in pattern and magnitude among the studied subjects of different age groups with no statistically significant difference, despite the fact that the regional myocardial velocities change due to aging.